It is known that viruses having a lipoid sheath are relatively sensitive and, thus, can be deactivated or even killed by the action of virucidal disinfectants known to date. A problem arises in combatting the naked viruses that are essentially more resistant to conventional disinfectants and, so far, could actually be killed only by applying formaldehyde at a relatively high concentration. However, formaldehyde is undesirable for toxicological reasons and is not applicable as a disinfectant for parts of the body either in laboratory tests or in clinical use.
The prior art literature on disinfecting or deactivating activities, respectively, of commercially available and skin-compatible disinfectants is contradictory. However, investigations conducted by the present inventors have resulted in the finding that most of the skin-compatible disinfectants are virtually ineffective against naked viruses. What has been reported on the effects of alcohols is also contradictory. Investigations conducted by the present inventors on the efficacy of isopropanol against naked vires showed that this alcohol is only very weakly active or ineffective against nakes viruses. These investigations further resulted in the finding that in a surprising manner ethanol and methanol are highly active and lose their activity only if they contain more than 30% of water. Thus, while ethanol acts as a disinfecting or deactivating agent, respectively, against bacteria and fungi even at a substantially lower concentration, the water content of the alcohols must be substantially reduced in order to accomplish a successful control or deactivation of nakes viruses.
As all alcohols, when applied to the skin, have an undesired effect of removing fat therefrom and rendering the skin brittle and chapped, it was a matter of choice to add skin-protecting agents to the alcohols such as to effect a restitution of the natural skin fat level. By corresponding investigations it has been found that, surprisingly, an addition of from 1 to 10% of glycerol to methanol and ethanol does not adversely affect the efficacy of these alcohols. It has further been found that additive amounts of up to 5% of castor oil also do not deteriorate the activity against naked viruses while the castor oil contributes to improve the skin compatibility.